As ruthenium complexes that constitute raw materials for forming ruthenium thin films by chemical deposition methods such as a CVD process and an ALD process, various ruthenium complexes have been known heretofore. As the ruthenium complexes that have been reported to be useful among those, the following ruthenium complexes are exemplified.

The above-mentioned two ruthenium complexes are such that carbonyl groups and a polyene having plural double bonds (cyclooctatetraene, cyclohexadiene) are coordinated as ligands for ruthenium. The reasons why these ruthenium complexes are useful as raw materials for chemical deposition method include, firstly, that they have high vapor pressures. A compound having a high vapor pressure can feed a raw material gas at a high concentration, and thus can improve film formation efficiency. Furthermore, these ruthenium complexes also have an advantage that the decomposition temperatures are relatively low. The advantage allows the film formation temperature to be set to a low temperature, and stable formation of a thin film while suppressing the damage of a substrate is enabled.